Without wishing to seem pedantic, resolution and precision are not the same thing, although they can overlap.
The resolution of a system may be millivolts, but it's overall error much larger, where the error is precision.
Perhaps a better question for you is:
Do you need 10mV of differential resolution (and what precision) or do you need 10mV of precision?
Cheers PeteS
10 mv out of what?
John
I've been using AD's nice 14-bit DDS chips, a pair of balanced 10mA fs current-source outputs with 14-bit resolution, which is 500mV fs, and 61uV or so lsb into 50 ohms.
Hi tt,
10mV is not that difficult to achieve if you get it indirectly.Imagine that you a 50ohm output impedance is desired. (as with most signal generators) Now produce a 1Vpeak-to-peak output, pass it through a voltage divider (say.. 10k on top, and 10ohm to ground) and at that midpoint, you have a 1mV signal and the output impedance is parallel combination of the two resistances to AC ground. (10 // (10k + 50) if the original signal generator had 50 ohm output). Then put a 40 ohm in series with the center tap and, there you have it.. a 50ohm impedance signal generator with a 1mV signal output and a relatively easy to create 1V signal input.
These kinds of attenuators are used all of the time when testing high gain circuits. I don't see any reason why it couldn't help you out here.. unless you want to go so low that you are greatly affected by thermal noise. :o)
This does limit the upper range of your signal generator (you would need
1000V for a 1V output), so perhaps voltages this low may require a special mode to be used. Depending on the frequency ranges you are looking at, a relay could switch between the modes fairly easily.I hope that helps a bit.
Best Regards, Adam Kumpf
snipped-for-privacy@mit.edu
that
Hi, All
My boss want a DDS signal generator having 10mv resolution output. Does that kind of stuff exist on the world? D/A Vref error, INL DNL error, amp op error and system noise would make 10mv not available. How could precise instrument achieve that kind of resolution?
Regards
Right, 50 ohms ... These parts use 400MHz clocks.
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